Organisms with multiple biotic attributes may also have conflicting niche determinants, and we assessed whether the realized niche reflects single or multiple biotic attributes. A group of all‐female salamanders found in eastern North America (unisexual salamanders; Ambystoma spp.) embody two potentially competing biotic states: hybridism and obligate reproductive parasitism. In theory, hybrids should occupy areas that are transitional to those used by parental species, parasites must live in syntopy with their hosts, and parasites that engage in ecological competition with hosts should be most successful in habitats that are moderately suitable for hosts. We built niche models for bisexual salamanders (Ambystoma laterale and Ambystoma jeffersonianum), as well as for unisexual Ambystoma that posses nuclear DNA from both of these species. These unisexuals are both phenotypic hybrids and obligate reproductive parasites of the bisexual species. We characterized realized niches predicted for unisexual Ambystoma via a hybrid‐framework model (e.g., using environmental predictors) and a parasite‐framework model (e.g., using host suitability predictors). Model validation using ancillary data permitted evaluation of which biotic state (hybrid vs. parasite) fit the observed patterns of occupancy. The hybrid model conformed strongly with predictions that the unisexual niche would be transitional between A. laterale and A. jeffersonianum bisexuals. Average annual temperatures and terrestrial salamander species richness (a proxy for competition) were particularly descriptive of parental niches and hybrid occupancy of transitional environments. While the parasite model behaved as expected, model validation did not fully corroborate its utility for determining patterns of occupancy. Instead, model selection revealed that the hybrid model was more descriptive of unisexual occurrence than the parasite model. Despite the fundamental importance of reproductive parasitism to the persistence of unisexual Ambystoma, we suggest that hybridism has greater contribution to the realized niche. When species have competing ecological attributes, one primary biotic state may dominate as a determinant of the realized niche.

中文翻译：

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a复合体中的利基决定因素：杂交或生殖寄生虫能解释分布模式吗？

具有多种生物属性的生物也可能具有冲突的生态位决定因素，我们评估了已实现的生态位是否反映了一种或多种生物属性。在北美东部发现的一组全雌性sal（单性sal；Ambystoma spp。）体现了两个可能竞争的生物状态：杂交和专性生殖寄生。从理论上讲，杂种应占据与亲本物种过渡的区域，寄生虫必须与其寄主同居，与寄主进行生态竞争的寄生虫应在适度适合寄主的生境中最成功。我们为双性恋sal建立了利基模型（Ambystomalaterale和Ambystoma jeffersonianum），以及拥有这两个物种的核DNA的单性Ambystoma。这些单性恋者既是表型杂种，又是双性恋物种的专性生殖寄生虫。我们通过混合框架模型（例如，使用环境预测器）和寄生虫框架模型（例如，使用宿主适应性预测器）对预测为单性Ambystoma的已实现生态位进行了表征。使用辅助数据进行模型验证可以评估哪种生物状态（杂交与寄生虫）符合观察到的居住模式。混合模型与单性生态位将在侧枝土壤杆菌和杰夫逊氏菌之间过渡的预测非常一致。双性恋者。年平均温度和陆地sal物种丰富度（代表竞争）特别描述了亲代生态位和过渡环境的混合居住。尽管寄生虫模型的行为符合预期，但是模型验证并不能完全证实其在确定居住模式方面的效用。取而代之的是，模型选择揭示了混合模型比寄生虫模型对单性发生的描述更多。尽管生殖寄生虫对单性Ambystoma的持久性具有根本的重要性，但我们认为杂交对已实现的利基市场具有更大的贡献。当物种具有相互竞争的生态属性时，一种主要的生物状态可能占主导地位，成为已实现生态位的决定因素。